It depends on your location, antenna, and the aircraft's elevation, but in the bay area I'll often pick up aircraft all the way out to Sacramento. Sometimes qui

It depends on your location, antenna, and the aircraft's elevation, but in the bay area I'll often pick up aircraft all the way out to Sacramento. Sometimes quite a bit further. Of course, the higher the aircraft the further you can "see" them. Most of the traffic I see is within 45 miles (especially low flying GA traffic), but I'll still pick up the occasional high altitude aircraft at 100+ miles out.